Lore

This is the same character as Dragonslayer Ornstein from the previous games. He left the ruined cathedral of Anor Londo to search the Nameless King. After reaching Archdragon Peak, he evidently discarded his armor and weapon in the same area where the Nameless King is encountered. It is speculated that Ornstein joined the Path of the Dragon covenant and possibly transformed into one of the many Dragon Men locked in prayer in the area. It has also been speculated that Ornstein may be the wyvern upon which the Nameless King rides during the first stage of the battle.

Theories

Title of theory.

Sources

Dragonslayer Spear
Cross spear associated with Ornstein the Dragonslayer. A weapon of the gods imbued with the strength of lightning.
Two-handed thrust utilizes the support of the cross and requires great might, but can pierce deep into the flesh of dragons, and send mere men flying.

Dragonslayer Helm
Golden lion helm associated with Dragonslayer Ornstein, from the age of gods, and imbued with the strength of lightning.
In the dragonless age, this knight, who long guarded the ruined cathedral, left the land in search of the nameless king.